The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 100 53 935.1, filed Oct. 31, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention relates to a press arrangement for processing a fibrous material web, in particular a paper or cardboard web.
2. Discussion of Background Information
Tandem-NipcoFlex-presses known up to now have been proven in operation. However, they are comparatively expensive and have a relatively long structural length. Additionally, when heavy paper types are used, a web tear can occur downstream of the pick-up roll.
The present invention provides an improved press arrangement in which the above-mentioned problems are eliminated. In particular, a compact structure is to be achieved in addition to a web guidance that is as continuous as possible downstream of the wire.
Accordingly, a press arrangement is provided for processing a fibrous material web, in particular a paper or cardboard web, having at least two press nips formed by two separate presses without a common center roll, in which the first roll, viewed in the web travel direction, is double-felted, and includes a suction press roll positioned on top, simultaneously embodied as a pick-up roll, as well as a mating roll positioned at the bottom.
Due to this design, an overall compact, inexpensive construction results which is particularly advantageous for modifications. Although press arrangements having a suction press roll assigned to a first roll and simultaneously serving as a pick-up roll are known from DE-A-199 02 139 and DE-A-199 12 497, in these known press arrangements the first and second roll, have a common center roll and/or at least one common felt.
A web tear downstream of the pick-up is avoided, even in the case of heavy papers, because a completely continuous web guidance is provided in the region downstream of the wire with the solution according to the invention. This solution results in an inexpensive double-felt press concept, in particular for even-sided paper.
Since the suction press roll is simultaneously provided as a pick-up roll, the fibrous material web can be accepted by a wire belt of the wire section via the upper felt guided over these suction press rolls.
In an exemplary embodiment of the press arrangement according to the invention, the mating roll allocated to the suction press roll is a sagging compensation roll or a crown bow compensation roll.
Here, this mating roll allocated to the suction press roll can be, in particular, a so called Nipco-F roll, i.e., a self loading roll.
The second roll, viewed in the web travel direction, is preferably a shoe press.
The second roll, viewed in the web travel direction, can preferably be double-felted.
In a practical embodiment of the press arrangement according to the invention, the press plane running through the second press nip is tilted in relation to the vertical.
Preferably, separate felts are guided through the first press nip and through the second press nip. Thus, it is advantageous not to provide a felt that is simultaneously guided through both press nips.
Generally, for example, it is also possible for an upper felt and a lower continuous belt, in particular a press belt, to be guided through the second press nip, viewed in the web travel direction. Here as well, the upper felt and the lower press belt are preferably guided through the second press nip only, i.e., not through the first press nip as well.
It is practical for the suction press roll to be blind bored and/or grooved in order to allow at least a partial dewatering by means of spinning off water.
Here, a gutter or collector is preferably allocated to the suction press roll that collects the water spun off the suction press roll. With the aid of the suction press roll positioned on top, the spun off water can be slowed down to some extent, allowing it to collect in a gutter or collector.
A practical embodiment of the press arrangement according to the invention is distinguished by the fact that, in the region of the transfer point, the upper felt, guided through the second press nip, is guided around a deflection roll, preferably embodied as a suction roll. It is practical for the upper felt, guided through the second press nip, to be guided around a deflection roll, preferably embodied as a suction roll, in the region of the transfer point.
In a useful practical embodiment, the fibrous material web is accepted by an upper felt guided through the second press nip in a region between the deflection roll, allocated to the lower felt of the first press, and another deflection roll allocated to this lower felt.
The press plane through the first press nip is advantageously tilted relative to the vertical.
The suction press roll is preferably driven. Additionally or alternatively, the mating roll allocated to this suction press roll can be driven as well.
In a preferred practical embodiment of the press arrangement according to the invention, the second press provided as a shoe press includes a shoe press roll positioned on top and a mating roll positioned at the bottom. Here, the mating roll is preferably driven.
Another advantageous embodiment of the press arrangement according to the invention is distinguished by the fact that the second press, viewed in the web travel direction, is single-felted, that the roll positioned at the bottom of the second press contacts the fibrous material web, and that at least one doctor is allocated to the roll positioned at the bottom.
The present invention is directed to a press arrangement for processing a fibrous material web that includes at least first and second presses arranged to form at least first and second press nips. The at least first and second presses are structured and arranged without a common center roll and without a common felt. The first press is a double felted press including a suction press roll and a mating roll, and is positioned upstream from the second press relative to a web run direction. The suction press roll is structured and arranged as a pick-up roll and is located on top of said mating roll.
Further, the material web can be a paper or a cardboard web. Also, the double felted press can include at least first and second felts arranged to sandwich the material web in said first press nip.
According to a feature of the invention, the arrangement further includes an upper felt guided around the suction press roll, which may be arranged to accept the material web from an upstream section of a web production machine. The upper felt can be arranged to accept the material web from a wire belt.
The mating roll can include a sagging compensation roll. Additionally, or alternatively, the mating roll may include a self-loading roll.
Further, the second press may include a shoe press. Additionally, or alternatively, the second press can be a second double felted press. The second double felted press may include at least first and second felts arranged to sandwich the material web in the press nip. Moreover, the double felted press may include at least first and second felts arranged to sandwich the material web in the first press nip, and the second double felted press comprises at least third and fourth felts arranged to sandwich the material web in the second press nip.
In accordance with another feature of the present invention, the second press may be arranged such that a press plane through the second press nip is oriented obliquely to vertical.
The press arrangement may further include an upper felt and a lower continuous belt guided through the second press nip. Further, the lower continuous belt can be a press belt. The upper felt and the lower continuous belt may be guided through the second press nip, but not through the first press nip.
According to a further feature of the instant invention, the suction press roll may include at least one of a blind bored and grooved surface. A gutter can be positioned in a region of the suction press roll to collect water spun off of the suction press roll.
Moreover, the press arrangement may include a deflection roll positioned between the first press and the second press. A lower felt of the first press can be arranged to guide the material web over the deflection roll and an upper felt of the first press may be separated from the material web and the lower felt in a region of the deflection roll. An upper felt of the second press can be arranged to accept the material web from the lower felt of the first press at a transfer point in a vicinity of the deflection roll. Further, the deflection roll may include a suction roll, the region of the deflection roll is upstream of the deflection roll, and the transfer point can be downstream of the deflection roll. Still further, a second deflection roll can be provided, around which the upper felt of the second press may be guided in a region of the transfer point. Another deflection roll can be provided around which the lower felt of the first press is guided, the another deflection roll may be located downstream from the deflection roll. The upper felt of the second press may be arranged to accept the material web from the lower felt of the first press in a region between the deflection roll and the another deflection roll.
According to a still further feature of the invention, the first press can be positioned such that a press plane through the first press nip is oriented obliquely with respect to vertical.
Further, the suction press roll can be a driven roll. Additionally, or alternatively, the mating roll may be a driven roll.
According to another feature of the present invention, the second press can include a shoe press roll and a mating roll. The shoe press roll can be positioned on top of the mating roll.
In accordance with yet another feature of the present invention, the second press can be a single-felted press. The single-felted press may include a roll having a surface arranged to directly contact the material web. The single-felted press can further include at least one doctor arranged against the roll surface. Moreover, the single-felted press may further include a shoe press roll positioned above the roll.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.